Hi If you get into “temperature nuts” territory, the triple point of water varies with the isotope “mix” in the standard. The “correct” mix turns out to be “mid continent deep well water”.
If you make a resonator that is very thick, you also need to make it very wide. If you don’t, the width to thickness ratio gets into things. You start having “modes” that couple and that messes things up. Since we are already into the area that this matters on a 5 MHz 3rd in modern packages ….. you make it thicker and you increase the mass. As you drop the frequency of a resonator, the acoustic loss goes down. To the degree that limits your resonator Q ( back to things like thickness to diameter) the Q would be much higher on a (say) 500 KHz SC than it is on a 5 MHz device. Q goes up and ADEV improves. Yes, that assumes that temperature fluctuations (or something weird) don’t get in the way. How you get an single isotope / zero contaminant quartz crystal - not at all clear. You have both silicon and oxygen involved. You have to grow the crystal in some sort of solution. You also have to ultimately start from a natural quartz seed ( you may be generations removed from it, but that’s still the starting point), Just for reference, your 5 MHz third is about a half inch in diameter. A 5 MHz 5th would be a bit larger in diameter to work well. Scale the third to 500 KHz and you are at 5” in diameter. Does it weigh 1 Kg yet? It would have to be a bit over an inch thick for that to be true. That’s about 10X to thick…… By the time you get to 200 KHz things are well over the target. Somewhere in the 250 to 400 KHz range (depending on a lot of things) would likely be the net result. Bob > On Apr 22, 2018, at 5:29 PM, Brooke Clarke <bro...@pacific.net> wrote: > > Hi: > > Isotopes of an element differ in the number of neutrons. The chemical > reactions of an element are governed by the electrons, which are the same for > all isotopes, so chemical means can not be used to separate the isotopes. > There are a number of ways of making the separation, for Uranium see: > https://en.wikipedia.org/wiki/Clinton_Engineer_Works#Facilities > > It's not clear to me how the isotopes of water are accounted for in it's > physical properties. Have these been refined and defined for each isotope? > This may be important since the properties of water show up a lot as the > basis for other definitions. > https://en.wikipedia.org/wiki/Isotopes_of_hydrogen > https://en.wikipedia.org/wiki/Isotopes_of_oxygen > > PS One of the names of the company I worked for was FEI Microwave. There was > a rumor that the funder of that company had a bunch of very special quartz in > the vault and that crystals cut from that material had better phase noise > than off the shelf crystals hence he had an advantage over other vendors. > http://prc68.com/I/Aertech.shtml#Names > > -- > Have Fun, > > Brooke Clarke > http://www.PRC68.com > http://www.end2partygovernment.com/2012Issues.html > > -------- Original Message -------- >> Single isotope diamond is 50% better thermal conductivity of normal >> diamond. It has been used in laser optics and thermal transfer >> applications (semiconductor heatsinks). I think the highest reported >> thermal transfer rate used isotopically pure diamond etched with >> micro-fluidic channels fed with coolant. GE makes the diamond material... >> it was developed as part of Reagan's Star Wars project. >> >> Isotopically pure silicon has 60% better thermal conductivity than natural >> silicon. >> >> Isotopically pure platinum has been used in RTD temperature sensors. >> _______________________________________________ >> time-nuts mailing list -- time-nuts@febo.com >> To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts >> and follow the instructions there. >> > > _______________________________________________ > time-nuts mailing list -- time-nuts@febo.com > To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > and follow the instructions there. _______________________________________________ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
